The History of Communication Leading Up to the 4G

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The First Generation of communication system is the Analog cellular system, means carrier is Analog. we just send wave forms primarily with voice. it is continuous in amplitude and time. variation in a signal disrupts over long distance . This Analog system was introduced in seventies.NMT , AMPS, TACS, CDPD technologies were used in 1G. It uses FDMA technique call to one country. All the Analog systems were used circuit switched technology and design only for voice communication not data. The cost for the system and voice transfer is also high in 1G.Problems with 1G is poor voice quality , less battery life , no security , the phone size is big and frequent call drops. second generation is digital cellular in this started sending 1's and 0's with the air. it is circuit switched and narrowband technology. It is low band digital cellular signaling system. Digital is more spectrally efficient it uses technologies like TDMA ,GSM,CDMA, iDEN , PDC, PHS.It uses digital modulation for better audio quality. GSM technology has both FDMA and TDMA techniques. An estimated GSM system users all over the world is 248 millions now and it is currently using in 140 countries. In addition to this , PDC(Personal Digital Communication) technology based on TDMA is introduced. After this CDMA technology was introduced , it divide speech into small segments and encoded to identify the calls by using spread spectrum. While GSM and TDMA systems are most important in 2G wireless technology, the CDMA technology proved that it gives better voice quality, low noise, few call drops , good security, and high network capacity. Data transmission, fax , messages up to 9.6 kbps is capable by 2G , but not acceptable for multimedia and web browsing applications.... ... middle of paper ... ...spectral efficiency schemes of modulation which cannot be applied to 3G infrastructure. The typical speed of 3G is limited to 2Mbps where as speed of 4G is up to 100Mbps and it also eliminate the interference caused by signal with high speed. 4G technology also provide uninterrupted voice, navigation and data services. This speed is achieved by OFDM modulation technique. Some of the other techniques used are use scheduling, power control and adaptive modulation, wireless millimeter and smart antennas. 4G requirements The advantages of 4G are high speed and it also has greater bandwidth it used multi hop and Adhoc network and the spectral efficiency of 4G is high, it has service portability and global access, it is IP based mobile system with less cost. We never seen 3G phone working on a 4G network. some carriers that have both 3G , 4G network like Verizon.

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